// addrspace.cc 
//	Routines to manage address spaces (executing user programs).
//
//	In order to run a user program, you must:
//
//	1. link with the -N -T 0 option 
//	2. run coff2noff to convert the object file to Nachos format
//		(Nachos object code format is essentially just a simpler
//		version of the UNIX executable object code format)
//	3. load the NOFF file into the Nachos file system
//		(if you haven't implemented the file system yet, you
//		don't need to do this last step)
//
// Copyright (c) 1992-1993 The Regents of the University of California.
// All rights reserved.  See copyright.h for copyright notice and limitation 
// of liability and disclaimer of warranty provisions.

#include "copyright.h"
#include "system.h"
#include "addrspace.h"
#include "noff.h"
#include "table.h"
#include "synch.h"

extern "C" { int bzero(char *, int); };

Table::Table(int s) : map(s), table(0), lock(0), size(s) {
    table = new void *[size];
    lock = new Lock("TableLock");
}

Table::~Table() {
    if (table) {
	delete table;
	table = 0;
    }
    if (lock) {
	delete lock;
	lock = 0;
    }
}

void *Table::Get(int i) {
    // Return the element associated with the given if, or 0 if
    // there is none.

    return (i >=0 && i < size && map.Test(i)) ? table[i] : 0;
}

int Table::Put(void *f) {
    // Put the element in the table and return the slot it used.  Use a
    // lock so 2 files don't get the same space.
    int i;	// to find the next slot

    lock->Acquire();
    i = map.Find();
    lock->Release();
    if ( i != -1)
	table[i] = f;
    return i;
}

void *Table::Remove(int i) {
    // Remove the element associated with identifier i from the table,
    // and return it.

    void *f =0;

    if ( i >= 0 && i < size ) {
	lock->Acquire();
	if ( map.Test(i) ) {
	    map.Clear(i);
	    f = table[i];
	    table[i] = 0;
	}
	lock->Release();
    }
    return f;
}

//----------------------------------------------------------------------
// SwapHeader
// 	Do little endian to big endian conversion on the bytes in the 
//	object file header, in case the file was generated on a little
//	endian machine, and we're now running on a big endian machine.
//----------------------------------------------------------------------

static void 
SwapHeader (NoffHeader *noffH)
{
	noffH->noffMagic = WordToHost(noffH->noffMagic);
	noffH->code.size = WordToHost(noffH->code.size);
	noffH->code.virtualAddr = WordToHost(noffH->code.virtualAddr);
	noffH->code.inFileAddr = WordToHost(noffH->code.inFileAddr);
	noffH->initData.size = WordToHost(noffH->initData.size);
	noffH->initData.virtualAddr = WordToHost(noffH->initData.virtualAddr);
	noffH->initData.inFileAddr = WordToHost(noffH->initData.inFileAddr);
	noffH->uninitData.size = WordToHost(noffH->uninitData.size);
	noffH->uninitData.virtualAddr = WordToHost(noffH->uninitData.virtualAddr);
	noffH->uninitData.inFileAddr = WordToHost(noffH->uninitData.inFileAddr);
}

//----------------------------------------------------------------------
// AddrSpace::AddrSpace
// 	Create an address space to run a user program.
//	Load the program from a file "executable", and set everything
//	up so that we can start executing user instructions.
//
//	Assumes that the object code file is in NOFF format.
//
//	"executable" is the file containing the object code to load into memory
//
//      It's possible to fail to fully construct the address space for
//      several reasons, including being unable to allocate memory,
//      and being unable to read key parts of the executable.
//      Incompletely consretucted address spaces have the member
//      constructed set to false.
//----------------------------------------------------------------------

AddrSpace::AddrSpace(OpenFile *executable) : fileTable(MaxOpenFiles) {
    NoffHeader noffH;
    unsigned int i, size;
	
	pageTableLock = new Lock("Page Table Lock");

	exeptr = executable;
	
    // Don't allocate the input or output to disk files
    fileTable.Put(0);
    fileTable.Put(0);

    exeptr->ReadAt((char *)&noffH, sizeof(noffH), 0);
    if ((noffH.noffMagic != NOFFMAGIC) && 
		(WordToHost(noffH.noffMagic) == NOFFMAGIC))
    	SwapHeader(&noffH);
    ASSERT(noffH.noffMagic == NOFFMAGIC);

    size = noffH.code.size + noffH.initData.size + noffH.uninitData.size ;
    numPages = divRoundUp(size, PageSize) + divRoundUp(UserStackSize,PageSize);
                                                // we need to increase the size
						// to leave room for the stack
    size = numPages * PageSize;

    //printf("size: %i, numPages: %i\n", size, numPages);


	#ifdef USE_TLB
	#else
    ASSERT(numPages <= NumPhysPages);		// check we're not trying
						// to run anything too big --
						// at least until we have
						// virtual memory
	#endif

    DEBUG('a', "Initializing address space, num pages %d, size %d\n", 
					numPages, size);
					
					
	//number of pages needed for each section
	#ifdef USE_TLB
	int codePages = divRoundUp(noffH.code.size, PageSize);
	int initPages = divRoundUp(noffH.initData.size, PageSize);
	int uninitPages = divRoundUp(noffH.uninitData.size, PageSize);
	#endif
					
// first, set up the translation 

	#ifdef USE_TLB
	iptLock->Acquire();
	spaceID = spacecounter;
	spacecounter++;
	iptLock->Release();
	#endif

	#ifdef USE_TLB
    pageTable = new PageTableEntry[numPages];
	#else
	pageTable = new TranslationEntry[numPages];
	#endif
	
	pageTableLock->Acquire();
    for (i = 0; i < numPages; i++) {
		pageTable[i].virtualPage = i;	// for now, virtual page # = phys page #
		
		#ifdef USE_TLB
		
		pageTable[i].physicalPage = -1;
		
		//setting the type of page		
		if(i < divRoundUp((noffH.code.size + noffH.initData.size), PageSize)){
			pageTable[i].byteOffset = noffH.code.inFileAddr + i*PageSize;
			pageTable[i].pageLocation = PageInExecutable;
			
		}
		else{
			pageTable[i].byteOffset = -1;
			pageTable[i].pageLocation = Other;
		}
	
		pageTable[i].timestamp = time(NULL);
		pageTable[i].swapLocation = -1;
			
		#else
		MainMemoryLock->Acquire();
			pageTable[i].physicalPage = usedpages->Find();			
		MainMemoryLock->Release();
		
		if(pageTable[i].physicalPage < 0){
			printf("Error: Not enough physical pages.\n");
			return;
		}
		
		#endif
		pageTable[i].valid = TRUE;
		pageTable[i].use = FALSE;
		pageTable[i].dirty = FALSE;
		pageTable[i].readOnly = FALSE;  // if the code segment was entirely on 
						// a separate page, we could set its 
						// pages to be read-only	
    }
	pageTableLock->Release();
    
// zero out the entire address space, to zero the unitialized data segment 
// and the stack segment
//    bzero(machine->mainMemory, size);

	#ifndef USE_TLB
	if (noffH.code.size > 0) {
        DEBUG('a', "Initializing code segment, at 0x%x, size %d\n", 
                        noffH.code.virtualAddr, noffH.code.size);
        executable->ReadAt(&(machine->mainMemory[pageTable[0].physicalPage * PageSize]),
                        noffH.code.size, noffH.code.inFileAddr);
    }
    if (noffH.initData.size > 0) {
        DEBUG('a', "Initializing data segment, at 0x%x, size %d\n", 
                        noffH.initData.virtualAddr, noffH.initData.size);
        executable->ReadAt(&(machine->mainMemory[pageTable[0].physicalPage * PageSize + noffH.code.size]),
                        noffH.initData.size, noffH.initData.inFileAddr);
    }
	#endif

}

int AddrSpace::MakeStackPages(){

	
	int stackPages = 8;
	int firstStackPage = numPages; //save the start of the stack pages

	#ifdef USE_TLB
	PageTableEntry * tempPageTable = new PageTableEntry[numPages + stackPages];
	#else
	TranslationEntry * tempPageTable = new TranslationEntry[numPages + stackPages];
	#endif
	
	pageTableLock->Acquire();
	/*Copy over the original page table*/
	for(int i = 0; i < numPages; i++){
	
		tempPageTable[i].virtualPage = pageTable[i].virtualPage;
		tempPageTable[i].physicalPage = pageTable[i].physicalPage;		
		tempPageTable[i].valid = pageTable[i].valid;
		tempPageTable[i].use = pageTable[i].use;
		tempPageTable[i].dirty = pageTable[i].dirty;
		tempPageTable[i].readOnly = pageTable[i].readOnly;
		
		#ifdef USE_TLB
		tempPageTable[i].pageLocation = pageTable[i].pageLocation;
		tempPageTable[i].swapLocation = pageTable[i].swapLocation;
		tempPageTable[i].byteOffset = pageTable[i].byteOffset;

		#endif
	
	}
	
	delete [] pageTable;
	pageTable = tempPageTable;
      
	numPages += stackPages;
       
	
	/*Extend page table by 8 pages to allocate to the stack, start with the first stack page*/
	for(int i = firstStackPage; i <  firstStackPage  + stackPages; i++){
	
		pageTable[i].virtualPage = i;
		#ifdef USE_TLB
			pageTable[i].physicalPage = -1;
			pageTable[i].pageLocation = Other;
			pageTable[i].byteOffset = -1;
			pageTable[i].swapLocation = -1;
		#else
			MainMemoryLock->Acquire();
			pageTable[i].physicalPage = usedpages->Find();
			MainMemoryLock->Release();
			if(pageTable[i].physicalPage < 0){
				printf("Error: Not enough physical pages.\n");
				return -1;
			}
		#endif
	
		pageTable[i].valid = TRUE;
		pageTable[i].use = FALSE;
		pageTable[i].dirty = FALSE;
		pageTable[i].readOnly = FALSE;  
		
		
	}
	
	#ifdef USE_TLB
	
	#else
		machine->pageTable = pageTable;
		machine->pageTableSize = numPages;
	#endif
	pageTableLock->Release();
	
	/*set the stack pointer to the bottom of the stack up 16*/
	return numPages*PageSize - 16;

}

void AddrSpace::ClearStackPages(int stackptr){
	
	MainMemoryLock->Acquire();
	int stackPages = 8;
	pageTableLock->Acquire();
	//save the last stack page
	int lastStackPage = (stackptr + 16)/PageSize;
	
	//start at the "First" stack page, and loop until the last one
	for(int i = lastStackPage - stackPages; i < lastStackPage; i++){
		
		//MainMemoryLock->Acquire();
		//printf("ClearStackPages: pageTable[i].physicalPage = %i; i = %i\n", pageTable[i].physicalPage, i);
			
			#ifdef USE_TLB
			iptLock->Acquire();
			if(pageTable[i].physicalPage != -1){
				ipt[pageTable[i].physicalPage].valid = FALSE;
				//iptUsedPages->Clear(pageTable[i].physicalPage);
			}
			iptLock->Release();
			
			pageTable[i].valid = false;
			
			#else
			usedpages->Clear(pageTable[i].physicalPage);
			#endif
		//MainMemoryLock->Release();		 
	
	}

	#ifdef USE_TLB
	
	#else
		machine->pageTable = pageTable;
	#endif
	pageTableLock->Release();
	MainMemoryLock->Release();


}

int AddrSpace::getNumPages(){
	return numPages;
}

//----------------------------------------------------------------------
// AddrSpace::~AddrSpace
//
// 	Dealloate an address space.  release pages, page tables, files
// 	and file tables
//----------------------------------------------------------------------

AddrSpace::~AddrSpace()
{
    delete pageTable;
}

//----------------------------------------------------------------------
// AddrSpace::InitRegisters
// 	Set the initial values for the user-level register set.
//
// 	We write these directly into the "machine" registers, so
//	that we can immediately jump to user code.  Note that these
//	will be saved/restored into the currentThread->userRegisters
//	when this thread is context switched out.
//----------------------------------------------------------------------

void
AddrSpace::InitRegisters()
{
    int i;

    for (i = 0; i < NumTotalRegs; i++)
	machine->WriteRegister(i, 0);

    // Initial program counter -- must be location of "Start"
    machine->WriteRegister(PCReg, 0);	

    // Need to also tell MIPS where next instruction is, because
    // of branch delay possibility
    machine->WriteRegister(NextPCReg, 4);

   // Set the stack register to the end of the address space, where we
   // allocated the stack; but subtract off a bit, to make sure we don't
   // accidentally reference off the end!
    machine->WriteRegister(StackReg, numPages * PageSize - 16);
    DEBUG('a', "Initializing stack register to %x\n", numPages * PageSize - 16);
}

//----------------------------------------------------------------------
// AddrSpace::SaveState
// 	On a context switch, save any machine state, specific
//	to this address space, that needs saving.
//
//	For now, nothing!
//----------------------------------------------------------------------

void AddrSpace::SaveState() 
{

	#ifdef USE_TLB
		IntStatus oldLevel = interrupt->SetLevel(IntOff); //turn off interrupts
		
		//invalidate TLB on context switch
		for(int i = 0; i < TLBSize; i++){
			
			if(machine->tlb[i].dirty == true && machine->tlb[i].valid == true){
				ipt[machine->tlb[i].physicalPage].dirty = true;
			}
			
			machine->tlb[i].valid = false;
		}

		(void) interrupt->SetLevel(oldLevel); //restore interrupts
	#endif




}

//----------------------------------------------------------------------
// AddrSpace::u State
// 	On a context switch, restore the machine state so that
//	this address space can run.
//
//      For now, tell the machine where to find the page table.
//----------------------------------------------------------------------

void AddrSpace::RestoreState() 
{
	#ifdef USE_TLB
	
	#else
		machine->pageTable = pageTable;
		machine->pageTableSize = numPages;
	#endif
}
